805 



LESLIE, SIR JOHN. 



LESSING, GOTTHOLD EPHRAIM. 



866 



by Dr. Adam Smith to assist in the education of his nephew Mr 

 Douglas, afterwards Lord Reston. In 17S8 he became tutor to two 

 Americans of the name of Randolph, junior students at the University 

 of Edinburgh, with whom he proceeded to Virginia, and after an 

 absence of about twelve months, during which time he visited New 

 York, Philadelphia, &c., he again returned to Scotland. In the early 

 part of 1790 he set out for London with recommendatory letters 

 from several individuals of literary and scientific reputation ; anc 

 among others from Dr. Adam Smith, who is said on this occasion to 

 have given him for advice, "never to approach an author whose 

 favour he was solicitous of gaining without first reading his works, 

 lest the conversation should turn that way." 



HU intention seems to have been to deliver lectures on natural 

 philosophy, but finding, to use his own words, that " rational lectures 

 would not succeed," he determined upon writing for periodical pub- 

 lications as the readiest means of obtaining a subsistence. He accord- 

 ingly began to furnish articles for the ' Monthly Review," and about 

 the same time was employed by Dr. William Thomson (whose 

 acquaintance he had originally made at St. Andrews University) to 

 collect and furnish notes for a Bible which was then being published 

 in parta. From the translation of Buffon's 'Natural History ol 

 Birds,' which appeared in 1793, in nine volumes 8vo, he derived 

 sufficient pecuniary emolument to lay the foundation of his subsequent 

 independence. 



In 1794 he visited Holland, and in 1796 he proceeded through 

 Germany and Switzerland, in company with Mr. Thomas Wedgwood. 

 Upon his return he became candidate for some professorship in the 

 University of St. Andrews, and shortly after for that of natural 

 philosophy at Glasgow, but in both instances was unsuccessful. In 

 1 799 he again set out upon a continental tour, and travelled through 

 Denmark, Norway, and Sweden, with Mr. Robert Gordon. 



In 1805 he offered himself as a candidate for the professorship of 

 mathematics in the University of Edinburgh, which had become 

 vacant by the promotion of Professor Playfair to the chair of natural 

 philosophy. At this period the only production of Mr. Leslie relative 

 to the pare mathematics consisted of an ' Essay on the Resolution 

 of Indeterminate Equations,' written about the time of his quitting 

 the university, and printed in the ' Edinburgh Philosophical Trans- 

 action!' for tli e year 1788; but he had published several papers on 

 diff-rent branches of physics in Nicholson's ' Philosophical Journal,' 

 and the Royal Society of London had recently awarded to him the 

 Rumford medals for his researches on the nature and propagation of 

 heat, an account of which had appeared the preceding year (' Experi- 

 mental Inquiry into the Nature and Properties of Heat,' Svo, 1804). 

 In addition to the reputation he had thus acquired, he came forward 

 with the warmest testimonials of Drs. Maakelyne and Hutton, Sir 

 Joseph Banks, Baron Maaeres, and other persons of distinction ; but 

 the appointment rested in the magistrates and town council of Edin- 

 burgh, subject to a clause in the charter of the university, which 

 declare* that the electors shall take advice of the clergy in the choice 

 of professors ; and these being desirous of promoting the election of 

 Dr. Thomas Macknight one of their own body, and a gentleman 

 perhaps equally qualified for the situation they therefore determined 

 upon opposing that of Mr. Leslie. They grounded their objection 

 upon a note in his ' Inquiry into the Nature of Heat ' (page 135, and 

 note 16, p. 522), wherein he refers to Hume's ' Theory of Causation,' 

 which be designates "a model of clear and accurate reasoning," 

 whence his clerical opponents somewhat illogically inferred that he 

 had rejected those arguments which are deducible from the observance 

 of nature in proof of the existence and attributes of a Creator. They 

 forthwith made a formal protest against his election, and expressed 

 their determination, in the event of his induction into the office of 

 professor, to prosecute for his immediate ejection. The town council 

 notwithstanding conferred the professorship upon Mr. Leslie, and the 

 clergy accordingly brought the affair before the General Assembly. 

 The debate which ensued (see 'Report of the Debate,' Svo, Edin., 

 1805), and which lasted for two days, was marked by strong party 

 spirit on the aide of the plaintiffs, and by the powerful and sarcastic 

 argument* of Sir Henry Moncrieff, who conducted the defence. Near 

 midnight on the second day (23rd of May 1805), the case was dismissed 

 as 'vexatious.' 



Mr. Leslie entered immediately upon his official duties, which he 

 continued to discharge with zeal and assiduity during the fourteen 

 following year*. In 1809, upon the death of Professor Playfair, he 

 wa called to the chair of natural philosophy, when his first care was 

 directed to the extension of the apparatus required in the more 

 enlarged series of experiments which he thought necessary for the 

 illustration of the course. "This indeed," says his biographer, Mr. 

 Napier, " was an object of which, from the first to the last hour of 

 bin incumbency, ho never lost sight ; and it is due to him to state 

 that it was through his exertions that the means of experimental 

 illustration, in the natural philosophy class, were first made worthy of 

 the university." He was knighted on the 27th of Juno 1832, and 

 died on the 3rd of November in the same year, at his seat at Coates 

 in Kifeahire, about two miles from the place of his birth. 



It was about the year 1794-95, while occupied upon a long series of 

 hygrometrical experiments, that he either re-invented or borrowed 

 f r om the ' Collegium Experimental ' of Sturmius his Differential 

 EIOG. LIV. VOL. in. 



Thermometer. He supposed the propagation of radiant heat to take 

 place by means of aerial pulsations, a supposition which appears 

 irreconcileable with the existence of radiation in vacua, and equally at 

 variance with the more recent experimental results of Messrs. Dulong 

 and Petit. He assumed moreover the universality of what is usually 

 termed Newton's law, namely, "that the decrements of heat of a 

 cooling body are proportional to the difference between its tempe- 

 rature and that of the surrounding medium ; " whereas it ia known to 

 hold only so long as that difference does not exceed from 40 to 50. 

 His own theories indeed sometimes appear to be rather the effusions 

 of a bold and active fancy than the logical deductions from any 

 established facts, and, as an almost inevitable consequence, the results 

 to which they lead him appear equally fanciful. Of this character are 

 his conclusions, that "the matter of the moon is phosphorescent, and 

 at some future period our satellite will become dim and seem blotted 

 from the blue vault of heaven ; " that " the earth contains a concavity 

 filled with concentrated light, shining with intense refulgence and 

 overpowering splendour," and others of like nature. He regarded the 

 inventive faculty as the highest with which the mind can be endowed, 

 and attached so little importance to inductive philosophy that he hag 

 been heard to deny that any merit is due to Bacon as its founder. As 

 an author, he was deficient in systematic arrangement and simplicity 

 of style. As a lecturer, he was liable to fall short of a satisfactory 

 elucidation of his subject by estimating too highly either the capacity 

 or the previous knowledge of his auditors. But on the other hand, 

 his active curiosity, varied reading, and powerful memory, led to the 

 acquisition of very extensive knowledge, which in many instances he 

 successfully applied to the promotion of science, and " his exquisite 

 instruments and experimental devices will ever attest the utility no 

 less than the originality of his labours." 



Besides the works noticed in the preceding part of this article, he 

 has left 



' Elements of Geometry, Geometrical Analysis, and Plane Trigo- 

 nometry," Svo, 1809; the same abridged, 1828; 'Geometry of Curvo 

 Lines,' 8vo, 1821; 'Philosophy of Arithmetic,' 1817; 'Account of 

 Experiments and Instruments depending on the relations of Air to 

 Heat and Moisture,' 12mo, 1813; 'Elements of Natural Philosophy,' 

 vol. i. (containing Mechanics and Hydrostatics), Svo, 1823. 



In the Edinburgh Philosophical Transactions: 'Observations on 

 Electrical Theories,' 1824 ; ' On certain Impressions of Cold trans- 

 mitted from the higher Atmospheres, with a Description of an 

 Instrument adapted to measure them,' 1818. 



In the Encyclopedia Bmtannica : Articles ' Achromatic Glasses ; ' 

 'Acoustics;' 'Aeronautics;' 'Andes;' 'Angle;' 'Angle, Trisection 

 of;' 'Arithmetic;' 'Atmometer;' 'Barometer;' 'Barometrical Mea- 

 surements ; ' ' Climate ; ' ' Cold and Congelation ; ' ' Dew ; ' ' Inter- 

 polation ;' 'Meteorology;' ' Progress of the Mathematical and Physical 

 Sciences during the Eighteenth Century.' 



In the Edinburgh Review : Papers on the ' Memoirs of the Society 

 of Arcueil ; ' on the ' History of the Barometer ; ' on ' Delambre's 

 Arithmetic of the Greeks ; ' on Von Buch'a ' Travels ; ' on Humboldt's 

 ' Physical View of the Equatorial Regions,' and his ' Travels;' on the 

 ' Attempts to discover a North- West Passage.' 



In Nicholson's Philosophical Journal, vols. iii. and iv. : 'Description 

 of an Hygrometer and Photometer;' 'On the Absorbent Powers of 

 different Earths ;' 'Observations on Light and Heat, with Remarks on 

 the Enquiries of Dr. HerscheL' 



Some papers by him on physical subjects were also read before the 

 Royal Society of London, but none were ever printed in their 

 ' Transactions.' 



(Memoir of Sir John Leslie, by Macvey Napier, 1838.) 



L'ESPINASSE, MADEMOISELLE, the name of a lady much 

 celebrated in the Parisian literary circles soon after the middle of last 

 century, was born in 1732. She is supposed to have been the ille- 

 gitimate daughter of people of rank. She was employed to read to 

 and converse with Madame du Deffand in her blindness ; but being 

 ambitious, well-informed, and eloquent endowed with much of what 

 the French call 1' esprit she attracted the interest of the circle sur- 

 rounding Madame du Deffand to an extant which greatly displeased 

 that lady. Mademoiselle 1'Espinasse was consequently dismissed, but 

 she had the boldness to plan, and the ability to execute, the collection 

 of a brilliant literary circle round herself. In 1764, when D' Alembert 

 Tell ill she nursed him with zeal, and thenceforth he resided in her 

 bouse. Marmontel, who in his 'Mdmoires' has given a very full 

 account of this lady, states that she made divers attempts to accom- 

 plish a high matrimonial alliance, and in one instance induced the 

 relations of a noble Spaniard on whom she had made an impression to 

 allow him to return to France, by procuring a false medical certificate 

 ;hat it was necessary to his health. Morellet, the uucle-in-law of 

 Marmontel, however in his 'Memoires' throws doubt on this story. 

 She died in 1776, to the great grief of D'Alembert, whom ehe had 

 "ong mortified by not returning his affection. Three volumes of her 

 ove-letters, conspicuous for ardent eloquence, were published in 1809. 



LEASING, GOTTHOLD EPHRAIM, was born on the 22nd of 



January 1729 at Kaiuentz in Upper Lusatia, of which place his father 



was pastor. His attachment to reading displayed itself from his 



iarliest childhood, and ho was a devourer of books at an age when 



thers are mere school-boys. Of his extraordinary diligence in study 



3 K 



